The stratum corneum or horny layer of the epidermis of the human skin contains certain water soluble cellular components which protect internal tissues from external forces. These cellular components are composed of, among other things, small polypeptides and amino acids, and permit the stratum corneum to absorb and retain water, thereby preventing dryness of the skin.
Several morphological changes, including a decreased moisture content of the stratum corneum, coupled with reduced eccrine and sebaceous gland output can decrease the presence of these components which protect the skin and allow for loss of collagen, the major skin protein. These morphological changes which result in a loss of integrity of the horny layer of the skin can be caused by a variety of conditions. Among such conditions are environmental, e.g. sun or wind exposure, trauma or wounds, e.g. cuts, burns or abrasions, exposure to chemicals such as alkaline soaps, detergents, liquid solvents, oils, preservatives, and disease, eg. eczema, psoriasis, seborrheic dermatitis.
A wound is tissue loss or damage anywhere in the body caused by physical or chemical means, chronic irritation and/or inflammation of body tissue. Agents known to be useful in wound repair include anti-inflammatory agents and locally applied agents useful in the production of collagen and fibrous tissue.
Psoriasis is a skin disease characterized by thickened patches of inflamed skin, often red and/or marked by scales. This abnormality involves the production of skin cells about ten times faster than normal. However, the rate at which old cells are shed remains unchanged. The result is the accumulation of live cells in patches covered with dead, flaking skin. Presently known treatments for this condition involve local application of agents to reduce the inflammation and reduce the overproduction of skin cells.
Eczema is an inflammation of the skin often accompanied by scaling or blisters. It is a form of allergy which generates an exaggerated immune response. Seborrheic dermatitis is a form of eczema. Presently known treatments involve local application of agents capable of inhibiting the immune response and reducing inflammation.
It has been known for some time that the use of amino acids in combination, and the interaction of such amino acids with vitamins, has an ability to encourage the retention of water by the stratum corneum and the formation of a protective film upon the surface of the skin. [See, e.g., B. Idson, Cosmetics and Toiletries, 77-79 (1978); Johnson et al, Cosmetics and Toiletries, 83-84 (1973)]. Oral vitamin therapy can alleviate certain skin conditions, however, topical application of vitamin preparations can create higher local concentrations of vitamins to the affected areas of the skin. [See, e.g., T. Hindson, Arch. Dermatol., 284-285 (1971)].
For example, compositions containing amino acids and vitamins have long been known to be used to treat skin conditions, including those affecting the hair, scalp, and nails. These compositions take the form of topical creams, shampoos, lotions and the like. Examples of such compositions are those described in Canadian Patent No. 828,729, U.S. Pat. Nos. 4,201,235, 5,133,958, International Patent Application Publication No. WO 92/00720, Great Britain Patent No. 857,243, U.S. Pat. Nos. 4,772,591, 3,849,576, European Patent Publication No. 70,048, U.S. Patent No. 5,135,913, 4,859,653 and 4,760,051. The compositions disclosed contain specific vitamins and amino acids either alone or in a variety of combinations. Although many prior art compositions have been described, their efficacy has been found to be inadequate. Consequently, in the treatment of a variety of skin conditions, particularly psoriasis, there is no prior art composition which has wide acceptance for a majority of individuals suffering with that condition.
There remains a need in the art, therefore, for topical compositions containing a specific combination of amino acids and ingredients which is efficacious in the treatment of a variety of skin conditions, e.g., wounds, environmentally caused inflammation, dry skin, psoriasis, seborrheic dermatitis, and eczema.